Wellington lies near five seismic faultlines and was the scene of the country's most powerful earthquake in 1855.

That devastating 8.2-magnitude quake caused four deaths and changed the city's entire geography, pushing the shoreline out 200 metres as it thrust the harbour floor upwards.

Anna Kaiser, a seismologist with the official GNS monitoring service, said it was impossible to predict how long the latest burst of activity would last.

"Certainly we expect aftershocks following an event like this," she said. "Unfortunately when we have something like this there's also an elevated chance of getting another earthquake of a similar magnitude."

New Zealand is on the boundary of the Australian and Pacific tectonic plates, forming part of the so-called "Ring of Fire", and experiences up to 15,000 tremors a year.